Deliver clean breaks for King (7)
I believe the answer is:
richard
'for king' is the definition.
(Richard I or Richard II)
'deliver clean breaks' is the wordplay.
'deliver' becomes 'rid' (e.g. deliver us from evil).
'clean' becomes 'char' (char can mean a cleaner).
'breaks' indicates putting letters inside (inserted letters break into the word).
'rid' placed around 'char' is 'RICHARD'.
(Other definitions for richard that I've seen before include "Play about hunchback" , "Boy's name - Cliff?" , "Mr Hannay" , "Name of three English kings" , "-- Wagner, composer" .)